Need help with Sterling 3306 on sterling goblet

[jerryfoote]

I have a set of 6 sterling silver goblets that have been in my family for at least 50 years. I cannot identify a manufactor to expand my set. Please help me. They weigh 136 gr. They are 6 3/4 in height, 3 7/16 across the mouth of the bowl, and 2 3/4 across the base. The only identifaction is the word sterling with the number 3306 under.
Thanks Jerry